878 M I 
Thefe people allow their milk to freeze in large quantity- 
in iron kettles ; and, when it is perfeblly congealed, they 
place it over a gentle fire to foften the edges of the cake, 
after which it may be taken out with a wooden fpa- 
tula. They commence thefe operations at the beginning 
of the cold, when they have milk in the greatelt abun¬ 
dance ; after which it may be preferved with great eafe 
throughout the whole winter. Mr. Fahrig, having fre¬ 
quent opportunities of feeing thefe cakes, foon obl'erved, 
that the furface of them was covered to a confiderable 
depth with a farinaceous powder; and, having eftablifhed 
a dairy upon the fame plan with thofe of the Moguls, he 
found the fame thing take place with himfelf. This pow¬ 
der was extremely fweet, and he received platefuls of it 
from the natives, who ufed it in their food, and fweetened 
their other victuals with it. Having cauled a number of 
cakes of frozen milk to be conveyed to the top of his 
houfe, where they were directly expofed to the violent 
cold, he found that the feparation of the faccharine pow¬ 
der was greatly promoted by this means. He fcraped the 
cakes every week to the depth of two inches, and after¬ 
wards fpread out the powder upon an earthen plate in or¬ 
der to deftroy the remains of moifture which might have 
prevented it from keeping for any length of time. W hen 
expofed in this manner it had a very agreeable and ffrong 
faccharine tafte; diffolved in warm water; and, when 
ftrongly ltirred by means of a chocoiate-ftick, would at 
all times produce an excellent and well-tafted milk. Raw 
milk affords a much larger quantity of this faccharine 
matter than fuch as has been boiled, or which has had the 
cream taken off it. Neither muff the milk be fuddenly 
expofed to the cold before it has loft its-natural heat; for 
the fudden contact of the cold drives all the cheefy and 
fat part towards the middle, while the external parts con- 
fift of little elle than water. In order to allow the parts 
of the milk to be all properly mixed together, Mr. Fahrig 
allowed the milk when newly taken from the cows to 
cool, and then poured it out into fnallow kettles. Mr. F. 
is of opinion that this method of treating milk would be 
of great fervice to navigators to fupply themlelves with 
milk during long fea-voyages ; and he allures us, from 
his own experience, that it will always fucceed, if proper 
attention be paid to it. He is of opinion, however, that 
all countries are not equally proper for the preparation of 
this faccharine matter; and indeed this feems very evi¬ 
dently to be the cafe, as the procefs appears to be a cryf- 
tallization of the faccharine parts of the milk, and a fe¬ 
paration of them from the aqueous ones by means of ex¬ 
treme cold. The country in which he made the experi¬ 
ments is one of the moll elevated in all Alia ; and fo cold, 
that, though it lies only in the 50th degree of north lati¬ 
tude, its rivers are frozen up for fix months of the year. 
The dry rarefied air increafes the evaporation from the 
ice-cakes, and leaves nothing but the faccharine or pure 
conftituent parts of the milk, which with the addition of 
water can always recompol’e the fluid. 
This account is confirmed by what we read in Von 
Buch’s more-recent Travels through Norway and Lap- 
land, (1806.) “ The milk of the rein-deer (fays he) they 
know how to preferve, by expofing it in autumn to the 
cold, and laying the frozen pieces up in ftore. After fe- 
veral months, this milk, when melted, is as good and 
pleafant as when it was frefh. If a ftranger comes to the 
hut, to whom fome civility muff: be Ihown, a frozen piece 
of milk is immediately placed near the lire ; and the guelt 
receives a fpoon, with which he ferapes off’ the thawed 
milk. When he is latisfied, the remainder is again put 
by in the cold for a future guelt. Such pieces are often 
brought down by the Laplanders for fide, and eagerly pur- 
chafed by the inhabitants of Alten.” 
When milk is fullered to coagulate fpontaneoully, the 
whey proves acid, and on Handing grows more and more 
io till the putrefa&ive Hate commences. Sour whey is 
ufed as an acid, preferably to the direbfly-vegetable or 
the mineral acids, in fome of the chemical arts 3 as for 
L K. 
diffolvingiron in orderto the ftaining of linen and leather. 
This acid was commonly made ufe of in the bleaching of 
linen, for diffolving and extrafting the earthy particles 
left in the cloth by the alkaline falts and lime employed for 
cleanfing and whitening it. Butter-milk is preferred to 
plain four milk or four whey : this lalt is fuppofed to give 
the cloth a yellow colour. Dr. Home, in liis ingenfous 
treatife on this fubjedf, recommends water acidulated with 
fulphuric acid (in the proportion of about half an ounce, 
or at raoft three quarters of an ounce, to a gallon), as pre¬ 
ferable in many refpefts to the acid of milk, or of the more- 
direbfly vegetable lubftances. Since this treatife appeared, 
the ufe of tour milk is very generally fuperleded by the 
lulphuric acid. 
It is obfervable, that affes’ milk is greatly difpofed, on 
Handing for a little time, to become thick and ropy. In- 
the Brellaw Collebtion for the year 1720, there is a remark¬ 
able account of milk (which probably was that of the afs) 
grown fo thick and tenacious as to be drawn out into 
long ftrings, which, when dried, were quite brittle. 
New cows’ milk, fuftered to Hand for fome days on the 
leaves of butterwort or fun-dew, becomes uniformly thick, 
flippery, and coherent, and of an agreeable fweet tafte, 
■ without any feparation of its parts. Frefh milk, added to 
this, is thickened in the fame manner, and this fuccef- 
lively. In lome parts of Sweden, as we are informed in 
the Swedifh Memoirs, milk is thus prepared for food. 
New milk has a degree of glutinous quality, fo as to be 
ufed for joining broken ftone-ware. There is a far greater 
tenacity in cheefe properly prepared. 
Milk, when examined by a microfcope, appears com- 
pofed of numerous globules fwimming in a tranfparent 
fluid. It boils in nearly the fame degree of heat with com¬ 
mon water; fome forts rather fooner, and lome a little 
later: after boiling, it is lefs difpofed to grow four than, 
in its natural ftate. It is coagulated by acids both mine¬ 
ral and vegetable, and by alkalies both fixed and volatile. 
The coagulum made by acids falls to the bottom of the 
ferum ; that made by alkalies fwims on the furface, com¬ 
monly forming (efpecially with volatile alkalies) a thick 
coriaceous fkin. The ferum, with alkalies, oroves green 
or fanious; with acids, it differs little in appearance from 
the whey that feparates fpontaneoully. The coagulum 
formed by acids is diffolved by alkalies, and that formed 
by alkalies is re-diffolved by acids ; but the milk does not 
in either cafe refume its original properties. It is coagu¬ 
lated by molt of the middle lalts, whofe baiis is an earth 
or a metallic body ; as l’olution of alum, fixed fit! ammo¬ 
niac, fugar of lead, green and blue vitriol; but not by 
the chalybeate or purging mineral waters, nor by the bit¬ 
ter fait extracted from the purging waters. Among the 
neutral falts that have been tried, there is not one that 
produces any coagulation. They all dilute the milk, and 
make it lefs difpofed to coagulate with acids or alkalies : 
nitre feems to have this effebt in a greater degree than the 
other neutral falts. It is inffantly coagulated by highly- 
rectified fpirit of wine, but fcarcely by a phlegmatic l’pi- 
rit. It does not mingle with expreifed oils. All thecoa- 
gula are diffolved by gall. 
It has generally been fuppofedby medical authors, that 
the milk of animals is of the fame nature with chyle, and 
that the human milk always coagulates in the ftomach of 
infants ; but, in a differtation upon the iubjebt by Mr. 
Clarke, member of the Royal Irifli Academy, we find 
both thefe pofitions controverted. According to him, 
woman’s milk, in a healthy ftate, contains no coagulable, 
mucilaginous, or cheely, principle, in its compoiition ; 
or it contains fo little, that it cannot admit of any fenfi- 
ble proof. Dr. Rutty ftates, that it does not afford even 
a fixth part of the curd which is yielded by cows’ milk ; 
and Dr. Young denies that it is at all coagulable either 
by rennets or acids. This is confirmed by Dr. Ferris, 
who in 1782 gained the Harveian prize-medal at Edin¬ 
burgh by a differtation upon milk. Mr. Clarke informs- 
us, that he has made a vait number of experiments upon 
woman’s 
